Sigma 900 MAX Refrigerated Sampler Instrument Manual

Page 62
Downlook Ultrasonic Sensor
8990sensors.fm
Section 4
4. Enter the ambient air temperature at the transducer location. For optimum
results, allow enough time (100 minutes) to ensure that the sensor is at
equilibrium with the surrounding ambient temperature. Press
ACCEPT.
5. Select the Liquid Depth method and enter the new level.
6. Take a physical measurement of the liquid depth (level) and enter
the value. Press
ACCEPT when finished.
4.1.3.2 Sensor Height
This method requires entering the distance between the face of the ultrasonic
sensor and the zero flow point in the primary device. The zero flow point in a
primary device is the level at which flow ceases. In a round pipe the zero flow
point would typically be the invert or bottom of the pipe. In a V-notch weir the
zero flow point occurs when the liquid behind the weir is level with the bottom
of the ‘V’. (There would still be liquid behind the weir plate but it would not be
contributing to flow). Sensor Height calibration is generally used when:
• Access to the primary device is difficult (such as confined space entry in a
manhole) or
• There is no liquid flowing during installation of the flow meter
1. From the Main Menu, select
OPTIONS>ADVANCED
OPTIONS>CALIBRATION>ULTRASONIC SENSOR.
2. Select Calibrate U-Sonic using the UP and DOWN keys. Press SELECT.
3. Select Standard as the type of Ultrasonic Transducer using the
CHANGE
CHOICE
key. Press ACCEPT to continue.
The speed of sound in air varies with the temperature of the air. The
ultrasonic sensor is equipped with temperature compensation to help
eliminate the effect of temperature variation under normal site conditions.
4. Enter the ambient air temperature at the transducer location. For optimum
results, allow enough time (100 minutes) to ensure that the sensor is at
equilibrium with the surrounding ambient temperature. Press
ACCEPT.
5. Select the Sensor Height method and enter the new level.
6. Enter the distance from the face of the transducer to the zero flow point of
the primary device.
7. Press
ACCEPT when finished.
4.1.3.3 Setting the Invisible Range
1. From the Main Menu, select OPTIONS>ADVANCED
OPTIONS>CALIBRATION>ULTRASONIC SENSOR.
2. Select the Invisible Range option using the UP and DOWN keys. Press
SELECT to continue.
3. Enter the Distance to End of the Invisible Range.